Fastener Installation Tool

ABSTRACT

A clinch-in fastener with a cylindrical body having a top, a bottom, sides and an axial internal bore. The fastener has a single shank at the bottom end of the body having a top surface orthogonal to the bore and a chamfer tapering to the bottom of the body. The top surface of the shank is adapted for receiving the cold flow of material surrounding a receiving hole of a workpiece. The shank may have a plurality of notches in its outermost edge that extend through both the top surface of the shank and the chamfer. The bore of the fastener extends completely through the fastener body from top to bottom and may be threaded. A fastener installation system having a tool with means for affixation to a rotary and vertically reciprocal element of an industrial machine. The tip of the tool has a distal end face with at least one arcuate displacer adapted for deforming a workpiece as the tool rotates and is pressed against the workpiece. A bore within the tip holds a fastener installed by the tool. The displacer is vertically and radially tapered along an arcuate ridge centered about the axial bore. The width of the displacer is also tapered to a point.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of non-provisional patent applicationSer. No. 16/307,133 entitled “Fastener and Installation Method for VeryThin Sheets” filed Dec. 4, 2018, which is incorporated herein byreference and priority from which is hereby claimed.

FIELD OF THE INVENTION

The present invention relates to fasteners, and methods of installing,that can be fastened to very thin sheet material. In one preferredembodiment, the fastener is a concealed head standoff fastener that isinstalled with a rotary punch.

BACKGROUND OF THE INVENTION

There are many fastening applications that require installation of athreaded fastener in a blind hole. For example, this installation methodis often used for assembling components of a waterproof apparatus.However, more often than not, this installation method is used when thecosmetic appearance of the apparatus is important and no blemish can bevisible on the surface after assembly.

Known self-clinching fasteners have a displacer and an undercut at thebottom of the fastener. The depth of the blind hole, and thus thematerial thickness of the sheet or component, must be large enough toaccept the full height of the displacer, undercut and shank.Furthermore, there must be additional material thickness below the holeto disperse installation stresses, and to eliminate or reduce markingduring installation to a point where any blemish can be removed in asecondary finishing operation. Therefore, many known self-clinchingfasteners can only be installed in relatively thick sheets orcomponents.

On the other hand, many applications, such as consumer electronics,require the assembly of relatively thin sheets or components. In oneknown assembly method, consumer electronic components are initiallyformed from a thick material. Then, to reduce the component's overallweight and stature, material is machined away everywhere except thefastening locations on the component, which retain the original(greater) thickness of the component. This process is costly andwasteful. Other methods of assembling thin sheets or components, such aslaser welding or adhesives, are impractical or not feasible inproduction due to material burn through or long cure times. Therefore,it would be desirable to provide a more efficient method of assemblingthin sheets or components. Since self-clinching fasteners are apreferred fastener type, it would be desirable to provide an improvedfastener and installation method having the advantages of self-clinchingfasteners but can be fastened in very thin sheets.

SUMMARY OF THE INVENTION

In one preferred embodiment, the present invention provides clinch-infasteners that can be installed by clinch-in fastening in holes of verythin workpieces, such as metal sheets, using novel tooling andinstallation methods. For example, the fasteners can be clinched in ablind hole as shallow as 0.014 inches deep. The clinch-in fastener ispreferably used with an installation tool that displaces sheet materialagainst and over structural features of the fastener that resist axialpull-out and torque. Moreover, the inventive fastener and installationminimize and/or eliminate marking or blemishes on the opposite side ofthe panel during installation.

Usually, self-clinching fasteners for thin panels require very tighttolerances. To ease this requirement, preferred embodiments of thefastener have a lead installation shank that has a chamfered leadsurface and an outer diameter that interferes slightly with the side ofthe hole.

In preferred embodiments, the shank is not actively pressed on by thetool during installation. Instead, a force is initially applied to thetop of the fastener to insert the fastener in the hole by overcoming theshank/hole interference. The force also holds the fastener in the holeduring clinching. In one preferred embodiment, the force is applied by aspring-loaded plate within an installation tool. Then, the installationtool rotationally presses material surrounding the hole and deforms itonto a top surface of the shank to clinch the fastener to the workpiece.

In one preferred embodiment of the invention, the fastener has acylindrical body with a top, a bottom, side walls, and an internal axialbore. The bore may extend entirely through the body. A single shank isfixed to and extends radially from the side walls near the bottom of thebody. The shank has a top surface, side surface and chamfer. The topsurface preferably lies in a plane that is orthogonal to the centralaxis of the body. The side surface is preferably co-axial with thecentral axis. The chamfer extends from the side surface at an angle thatis skew to the central axis. The chamfer tapers downwardly-inwardly fromthe side surface towards the bottom of the body. The top surface of theshank is constructed and arranged to receive the cold flow of workpiecematerial surrounding a hole in a workpiece.

In another preferred embodiment, the shank includes a plurality ofperipheral notches. At least one of the notches is preferably formed inan outermost edge of said shank. At least one notch may extend throughthe top surface of the shank, the side surface, the chamfer, or acombination of those surfaces.

Another preferred embodiment of the invention comprises an assembly ofthe clinch fastener described above affixed in a blind hole of aworkpiece. The workpiece may preferably be a planar sheet of aluminum.The fastener is affixed to the workpiece by displacing materialsurrounding the hole onto at least the top surface of the shank. Thedisplaced material may also fill one or more of the notches in thefastener shank. In one embodiment, at least one of the internal threadsof the fastener is covered with material displaced from a central raisedarea of workpiece material in the receiving hole.

The fastener may have a variety of shapes and functionality. Forexample, in one embodiment, the fastener may be a concealed headstandoff. In another preferred embodiment, the fastener may comprise atwo-part fastener arrangement for connecting cooperating panels. In thisembodiment, for example, one fastener may be a floating-pin retainerwhile the other may be a magnetic release gripper. In this latterembodiment, the fasteners interconnect to join the cooperating panelstogether such as the casing of a laptop computer.

In another preferred embodiment, the invention comprises a fastenerinstallation system having an installation tool adapted for affixationto an element of an industrial machine that rotates and translates.Preferably, the industrial machine is CNC milling machine, which appliessimultaneous rotational and translational motion, especiallyvertically-downward motion, to the tool as the fastener is installedinto the workpiece.

The tool has a spindle at its top end, which can be removably affixed tothe industrial machine. At its bottom end, the tool has a tip with adistal end face (relative to the spin. At least one displacer is fixedto the distal end face, which is constructed and arranged to deform theworkpiece as the tip rotates and is pressed against the workpiece. Anaxial bore in the tip holds the fastener to be installed by the tool.Preferably, the distal end face is orthogonal to the axial bore.

In preferred embodiments, the displacer is vertically and radiallytapered along an arcuate ridge centered around the axial bore in thetip. An inside edge of the displacer is chamfered from the ridge to theaxial bore and chamfered from the displacer ridge to an outer edge ofthe displacer. The displacer is preferably vertically tapered along thearcuate ridge. The taper extends from a first end of greatest heightdown to a second end of zero height. The displacer blends into the endface of the tool at the second end. The width of the displacer is alsotapered such that one end of the displacer(s) intersects the end face ata point.

In one embodiment, the tool has two identical displacers located 180degrees apart. In one preferred embodiment, the length of each displaceris defined by approximately 90 radial degrees of extension from thefirst end to the second end.

The tool may have fluid communication means extending from the spindleto the tip. The fluid communication means preferably comprises fluidflow channels that connect a vacuum source to the tip. The vacuumcreated at the tip holds the fastener within the tip bore while the toolrotates.

In another embodiment, the invention provides a method of rigidlyaffixing a fastener, such as described above, to the workpiece bydisplacing workpiece material against the fastener. After the fasteneris pressed into the blind receiving hole, material surrounding orproximate the hole is displaced against the fastener by simultaneouslypressing the tool against the workpiece and rotating the tool.Preferably, the material is displaced onto the top surface of thefastener shank. The fastener and workpiece should be supported by a hardsurface such as an anvil. In another embodiment, the material isdisplaced into at least some of the threads of the internal bore of thefastener.

In a further preferred embodiment, the invention provides method ofclinch-in fastening a fastener in a blind hole of workpiece. The methodincludes the initial steps of providing a fastener and inserting thefastener in the blind hole. Then, workpiece material surrounding theblind hole is displaced against the fastener by: (a) applying alocalized force to a segment of the workpiece material proximate theperimeter of the hole. The localized force has force components in boththe parallel and perpendicular direction relative to the plane of theworkpiece; (b) increasing the localized force until it induces the yieldstress in the workpiece and workpiece material deforms radially towardthe fastener; (c) radially advancing the localized force around the holeperimeter to a new segment; and, (d) repeating steps (a)-(c) until thelocalized force has been applied to the entire perimeter of the hole.Preferably steps (a)-(d) are repeated until a sufficient amount ofworkpiece material has been deformed into contact with the fastener toclinch the fastener in the hole.

In a preferred embodiment, the localized force is applied to theworkpiece with a rotatable tool having displacer adapted for deformingthe workpiece. Due to its shape, the displacer applies both components(perpendicular and parallel to the plane of the workpiece) of thelocalized force when the displacer is driven normally into the surfaceof the workpiece. In another preferred embodiment, the displacer appliesboth components of the localized force when the displacer is drivennormally into the surface of the workpiece and is simultaneously rotatedaround the perimeter of the hole.

These methods are preferably used with the clinch-in fasteners describedabove. Workpiece material is deformed onto the top surface of the shank,and optionally into at least one of the threads of the internal bore.The fastener is initially pressed into the blind hole by thespring-biased pusher of the above-described tool.

The inventive fastener, tooling and installation methods provide manyadvantages over the prior art. For example, embodiments of the inventionprovide one or more of the following features and advantages.

The displacer is eliminated from the fastener. Instead, it isincorporated into the installation tool. As a result, the minimum holedepth in the workpiece is reduced. This construction also effectivelyeliminates the undercut in prior art self-clinching fasteners.

Prior art self-clinching fasteners usually include a feature on thedisplacer that prevents rotation. In embodiments of the presentinvention, the anti-rotation feature is incorporated into the fastenershank.

The very thin panels of consumer electronic products, and the very smallfasteners used to assemble panels, require a very tight tolerance. Toaccount for this small tolerance, the inventive fastener has a chamferedlead installation edge on a shank that will interfere slightly with thediameter of the hole.

The fastener is not actively pressed on during installation. Instead,only a small force is initially needed to press the fastener through theinterference between the shank and the hole, and then stabilize thefastener in the hole. The tool includes a spring loaded punch, which iscapable of exerting this small initial force. The tool can also exert amuch larger force directly on the workpiece to cold deform the workpieceonto the fastener.

The cross section of the displacer is wedge shaped to deform (plows)metal inwardly and onto the top of the fastener shank. Unlike on thefastener, this geometry may be readily formed on the installation tool.

The axial component of the high installation force on prior artself-clinching fasteners can cause excess stress and be carried throughto the cosmetic face. In preferred embodiments of the invention, theamount of axial force needed to cold deform the workpiece is reduced byusing a rotating wedge. Torque is employed to plow metal over thefastener shank. The amount of axial force is reduced by reducing thecross-sectional area of material being pressed into the panel, byredirecting the axial force into the horizontal orientation with thedisplacers, and deforming material radially toward the fastener.

Because the installation will require both torque and axial force forinstallation, equipment must be employed that has this capability. CNCmilling machines are used to cut the shallow, flat bottomed installationholes. According to the invention, the same machine, in the sameoperation, then changes tools automatically and installs a fastener intothe hole that was just created. This method eliminates the need forseparate installation equipment and the need to handle parts through twooperations. This method creates a great economic benefit for theassembly of small consumer electronics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a fastener in accordance with apreferred embodiment of the invention;

FIGS. 2 and 3 are cross-sections showing the fastener of FIG. 1 and aninstallation tool at sequential steps as the fastener is installed in aworkpiece in accordance with a preferred embodiment of the invention;

FIG. 4 is a perspective view of the bottom, distal surface of the toolshown in FIGS. 2 and 3 ;

FIGS. 5 a, 5 b and 5 c schematic illustrations of distal end surfaces ofvarious tools;

FIG. 6 is a graph that illustrates the beneficial force profile of theinvention;

FIG. 7 is a perspective view of a receiving hole in a workpiece inaccordance with another preferred embodiment of the invention;

FIG. 8 is a cross-section showing the fastener of FIG. 1 andinstallation tool as the fastener is installed in the receiving holeshown in FIG. 7 in accordance with a further preferred embodiment of theinvention;

FIG. 9 is a cross-section of an installation tool in accordance withanother preferred embodiment of the invention;

FIG. 10 is a cross-section of an installation tool in accordance with afurther preferred embodiment of the invention;

FIG. 11 is a cross-section of a two-part fastener for joining twoworkpieces in accordance with an additional preferred embodiment of theinvention;

FIG. 12 is a perspective view of a fastener in accordance with anotherpreferred embodiment of the invention; and,

FIG. 13 is a side elevation of the fastener of FIG. 12 .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

“Self-clinching fastener” means any device, usually threaded, that, whenpressed into ductile metal, displaces the host material around themounting hole, causing it to cold flow into a specially designed annularrecess in the shank or pilot of the fastener.” “Clinch-in” fastenermeans any device, usually threaded, that, can be mechanically fastenedin a blind receiving hole of a metal workpiece by cold deforming themetal surrounding the hole into contact with the device. “Clinch-infastening” as used with reference to a fastener and metal workpiece isused in its broadest send to mean the process of joining the fastener tothe workpiece (without additional components) using a tool toplastically deform the workpiece into contact with the fastener to forma mechanical interlock between the fastener and the workpiece.

A fastener in accordance with a preferred embodiment of the invention isshown in FIGS. 1-3 and 6 , and is designated generally by referencenumeral 11. Referring to FIG. 1 , the fastener generally comprises acylindrical body 13 having an axial, threaded bore 12 that extendscompletely through the body 13 from the top 13 a to the bottom 13 c ofthe body 13. In one preferred embodiment, the top and bottom of the bodyare flat and the side walls are cylindrical. However, one or more ofthose surfaces may be curved, tapered, or have a different regular orirregular geometry in other preferred embodiments.

At the bottom 13 c of the body 13, a shank 15 protrudes radially fromthe side walls 13 b. The shank has a top surface 17, a side surface 18,a chamfer 14, and a bottom surface 16. In a preferred embodiment, thetop surface 17 of the shank 15 is flat, annular and lies in a plane thatis orthogonal to the central axis of the body, and parallel to the top13 a and bottom 13 c of the fastener body 13. Preferably, the sidesurface 18 is cylindrical, and co-axial with and parallel to the sidewalls 13 b of the body 13. Preferably the chamfer surface 14 extends atan angle that is skew to the central axis of the body, and tapersdownwardly-inwardly from the side surface 18 towards the bottom 13 c ofthe body 13.

In one preferred embodiment, the bottom surface 16 of the shank 15 isflat, annular and lies in a plane that is orthogonal to the central axisof the body 13, and parallel to the top 13 a and bottom 13 c of the body13. In a preferred embodiment, the bottom surface 16 is continuous andco-planar with the bottom 13 c of the body 13. By locating the shank atthe very bottom of the body, the minimum thickness of the workpiece canbe minimized. In other embodiments, the chamfer may blend directly intothe bottom of the body, thereby eliminating the bottom surface of theshank.

In the embodiment shown in FIGS. 1-3 , the shank 15 includes a shortside surface 18, which functions to control the diameter of the shankduring manufacturing. It is theoretically possible to eliminate the sidesurface. However, if the flat top surface 17 and chamfer 14 werecontiguous, they would likely form a metal burr on a sharp edge duringmanufacturing. For practical handling, the burr would need to be trimmedoff, thereby leaving a straight side surface. Therefore, the sidesurface is preferable to control the quality and dimensions of the shankdiameter.

In one preferred embodiment, the top 17 surface, side surface 18,chamfer 14 and bottom surface 16 are illustrated and described asplanar. However, one or more of those surfaces may be curved, tapered,or have an irregular shape in other preferred embodiments.

The top surface 17 of the shank 15 is adapted to receive the cold flowof material surrounding a blind hole in a workpiece 21 such as seen inFIGS. 2 and 3 . The shank 15 includes a plurality of notches 19, whichalso receive displaced material to provide torque resistance once thefastener 11 is installed in the workpiece 21. In a preferred embodiment,the notches 19 are equally spaced around the perimeter of the shank.Preferably, the notches 19 extend through a portion of both the topsurface 17 of the shank 15 and the chamfer 14.

FIGS. 2 and 3 illustrate a method of installing the fastener 13 in ablind hole of a workpiece 21 in accordance with a preferred embodimentof the invention. Preferably, the fastener 13 is installed in two stepsusing a novel installation tool 20, which pushes the fastener 13 intothe blind hole and displaces (cold deforms) the material around theperimeter of the hole onto the top surface 17 of the shank 15. Theworkpiece 21, is made from a material that allows the cold flow ofmaterial when compressed.

In the embodiment shown in FIGS. 2 and 3 , the tool 20 generallycomprises a cylindrical tool body 24 having an axial, proximal end 24 a,cylindrical side walls 24 b, and an axial, distal end 24 c having acentral, axially-extending blind bore 30. Wedge-shaped displacers 27extend axially from the distal end 24 c of the tool body 24 andpreferably surround the opening of the bore 30. The tool 20 has acompression spring 25 seated at one end in the bottom of the bore 30,and connected at the other end to a push plunger or “pusher” 22. Thepusher 22 is constructed and arranged to exert an axial displacementforce on the top surface 13 a of the fastener 13 when the fastener ispartially inserted in the bore 12. The pusher 22 preferably has a shapeand size that compliments the shape and size of the central bore 30 andpermits the pusher 22 to freely reciprocate within the bore 30 withoutbinding. The compression spring 25 controls the magnitude of theinstallation force of the pusher 22 on the fastener, thereby reducingthe possibility of pressure marking on the back side of the panel. Thespring 25 also isolates the high installation force of the displacer(described below) from pressing on the fastener as well, reducing thepossibility of pressure marking by reducing the area in highcompression.

The working end or tip 40 of the installation tool 20 of FIGS. 2 and 3is shown in greater detail in FIG. 4 . The distal end surface 24 c ofthe tip 40 is orthogonal to the axial bore 30 for engaging theworkpiece. The tool 20 has at least one displacer 27 on the tip 40. Inthe embodiment shown in FIG. 4 , the tool 20 has two, identical,diametrically-opposed displacers 27. The displacers 27 are bothvertically and radially tapered along an arcuate ridge 31 that iscentered about the axial bore 30. Each displacer 27 is chamfered fromthe arcuate ridge 31 inwardly to the axial bore 30 and is also chamferedfrom the arcuate ridge 31 to an outer edge 32. Each displacer 27 isvertically tapered along the arcuate ridge 31 from one end of greatestheight (the “back end 33” based on the intended direction of rotation)down to an opposite end (the “front end 34” based on the intendeddirection of rotation) of zero height where the ridge 31 meets the endface 24 c. Furthermore, the width of the displacers 27 is tapered fromits maximum width at the back end 33 to its minimum width at the frontend 34. At the front end 34, the width of the displacers 27 intersectsthe working surface 24 c at a point.

In this embodiment, the two displacers 27 are located approximately 180degrees apart. The displacers 27 are identical and the length of eachdisplacer 27 measures approximately 90 radial degrees about the toolcentral axis from the one end 33 to the other end 34. Compared to priorart flat-faced displacers having a rectangular cross-section, the wedgedisplacers 27 of the invention push some metal radially inward as theymove downwardly into the workpiece.

Referring to FIG. 2 , a fastener 13 is initially inserted into thecentral bore 30 of the tool 20 until the top surface 13 a abuts thepusher 22. In this position, the fastener 11 is held within the tool 20with a portion of the fastener, including the shank 15, protruding fromthe bore opening. The bottom 13 c and shank 15 of the fastener 11 isthen pressed against the perimeter of receiving hole 23 in the workpiece21 by the pusher 22 as shown in FIG. 2 . The chamfer 14 on the shank 15helps center the fastener 11 in the hole 23.

Referring to FIG. 3 , the tool 20 next moves downwardly to insert thefastener 11 in the hole 23. In preferred embodiments, the diameter ofthe shank 15 is nearly exact or slightly larger than the diameter of theblind hole 23 to account for very tight tolerances of very smallfasteners and very thin sheets. The stiffness of the spring 25 createsenough force on the top surface 13 a of the fastener 11 to overcome this“interference zone” and press the fastener 11 into the hole 23. As thefastener 11 moves downwardly, the shank cold deforms some materialsurrounding the hole 23 into abutting interface with the chamfer 14.

Once inserted in the hole, the pusher 22 continues to steady and supportthe fastener in its upright position. Next, the tool translates furtherdownwardly until the displacers 27 contact the workpiece. When the forceof the displacer on the workpiece induces the yield stress into theworkpiece material, rotation of the tool is preferably initiated. As thetool rotates, the displacers 27 cold deform inwardly the materialsurrounding the blind hole 23 onto the top surface 17 of the shank 13and preferably into one or more of the notches 19. As deformation occursand material is pushed radially, the yield stress on the workpiecegradually reduces if the displacers are not pressed further into theworkpiece. Therefore, as rotation and radial deformation occurs, thetool translates continuously downward to maintain a steady force in theworkpiece in excess of the yield stress. This process continues until asufficient amount of material has been displaced onto the top of thefastener flange 15 to lock the fastener 11 in the workpiece 21.

The amount of force on the fastener and workpiece, and the amount ofwork, required to install a fastener 11 in accordance with preferredembodiments of this invention is less than the prior art methods using adisplacer with a flat face. In prior art self-clinching fasteners, thedisplacer has a rectangular cross section, which deforms (pushes) allmaterial in a downward direction and causes material to bulge into anundercut. In contrast, the wedge-shaped displacers 27 deform (push) somemetal material radially inwardly as they move downwardly. Since thenarrow apex or arcuate ridge 31 of the displacer 27 first contacts theworkpiece, the force on the workpiece at the beginning of thedisplacement is very low. Then, for every increment of downward verticaldisplacement, the force on the workpiece increases until the displacer27 is fully embedded. While this force gradually increases, this forceis always lower than force exerted by a comparable, prior art,flat-faced displacer having a base and height equal to the base andheight of the tapered displacer 27. Once the tapered displacer 27 isfully-embedded, the respective forces are nearly equal. This comparisonof forces is graphically illustrated in FIG. 6 .

Furthermore, since the amount of work is the product of force anddistance, the amount of work exerted by the tapered displacer is muchlower than its prior art counterpart. The reduction in work to deform anequal amount of material compared to the prior art is also illustratedin the graph of FIG. 6 . The area shown in the hatched portion of thediagram represents the amount of work that is saved using a wedgedisplacer. 27.

In preferred embodiments, the tool is rotated counterclockwise withrespect to the embodiment shown in FIG. 4 and clockwise in the directionshown in FIGS. 5 a-c , wherein the narrow, pointed end of the displacer27 leads.

The aforementioned force reduction permits clinch-in attachment of thefastener 11 into a very thin workpiece 21 such as an electronics panel.Even when applied into a blind hole as shown in FIGS. 2 and 3 , nodistortion can be seen on the opposite side of the workpiece 21, whichis very important to the aesthetic appearance of consumer products.

The above-described force reduction also is achieved in part because thedisplacers 27 are located on the installation tool 20 and not on thefastener 11, and because the displacers 27 are wedge shaped and notrectangular with a flat bottom working surface. This tool constructioncan therefore be used with a fastener having a very shallow shank. As aresult, the fastener and workpiece have a strong attachment but haveminimal displacement of the workpiece material.

FIGS. 5 a-c schematically illustrate the tips of three installationtools. The shaded areas represent the cross section of the base of thedisplacer on each tool. The fastener is staged in the center hollow areaof each tool.

The tool shown in FIG. 5 a represents a simple ring displacer “RD” onthe face “F” of a prior art, self-clinching fasteners “SCF”, which ispressed axially only onto the workpiece. The tools shown in FIGS. 5 band 5 c represent tools in accordance with preferred embodiments of theinvention having a single (FIG. 5 b ) and a pair (FIG. 5 c ) ofdisplacers 27. The force necessary to clinch workpiece material usingeither of these tools is F=P/A, where P is the pressure that is equal tothe yield stress of the workpiece and A is the cross-sectional area ofthe ring displacer (represented by the shaded area). The tools shown inFIGS. 5 b and 5 c are rotated in the direction shown by the rotationarrows. When rotated, both tools in FIGS. 5 b and 5 c will displace thesame amount of material as the tool shown in FIG. 1 when rotated throughat least 360 and 180 degrees, respectively. If both tools of FIGS. 5 b-care pressed into the workpiece and rotated 360 and 180 degrees,respectively, the displacement effect is the same as when the prior arttool of FIG. 5 a is axially pressed into the same workpiece. Bycomparison to the prior art, much of the installation work is expendedas torque with the rotational tapered displacers compared to axialdisplacement with the prior art.

The cross sectional area of the displacer of FIGS. 5 b and 5 c isone-sixth (⅙) and one-third (⅓), respectively, of the displacer shown inFIG. 5 a . Therefore, the resulting axial force necessary to press thesetwo displacers into the workpiece is also one-sixth (⅙) and one-third(⅓), respectively, of the displacer shown in FIG. 5 a.

Of the two preferred embodiments shown in FIGS. 5 b and 5 c , thedual-displacer embodiment shown in FIG. 5 c is preferred. With only asingle displacer 27, the flange may be loaded unevenly duringdeformation, which can dislodge the fastener before installation iscomplete.

A tool 120 and method of installing a clinch fastener in a thinworkpiece in accordance with another preferred embodiment is illustratedin FIGS. 7 and 8 . In this embodiment, the receiving hole 123 of theworkpiece 21 is donut shaped and has a central raised area of materialforming a central knob 143. The knob 143 can be formed by known methodssuch as removing the material around the knob 143 when the hole 123 isformed.

The tool 120 has a construction similar to the tool 20 described withreference to FIGS. 2 and 3 . The tool 120 generally comprises acylindrical tool body 124 having an axial, proximal end (not shown),cylindrical side walls 124 b, and an axial distal open end 124 c havinga central, axially-extending blind bore 130. Wedge-shaped displacers 127extend axially from the distal end 124 c of the tool body 124 andpreferably surround the opening of the bore 130. However, in thisembodiment, the tool includes a central, center punch 145 extendingaxially from the bottom of the bore 130. The punch 145 has a pointeddistal tip 146. Similar to the tool 20 of FIGS. 2 and 3 , the tool 120has a spring-biased pusher 147; however, in this embodiment, the pusher147 has a central aperture through which the punch 145 extends.

The tool 120 is used to install a fastener 11 in the same manner, andusing the same steps, as described with respect to the first tool 20.The fastener 11 is held in position against the panel 21 by the pusher122. The spring-biased pusher 122 supports the fastener in the blindhole 123 as the displacer 127 cold deforms material surrounding theouter perimeter of the hole 123 onto the top 17 of fastener shank 15.However, in addition, as the tool 120 moves downwardly, the center punch145 cold deforms the knob 143 outwardly and into at least one of thethreads of the fastener 11 at the same time that the displacers 127 colddeform material around the perimeter of the hole 123 inwardly and ontothe top surface 17 of the shank 15. The cold deformation of the knob 43preferably occurs at the same time as deformation at the outer perimeterof the hole 123. This construction creates a more secure connectionbetween the fastener 11 and the workpiece 21.

An installation tool in accordance with an additional embodiment of theinvention is shown in FIG. 9 and is designated generally by referencenumeral 220. The tool 220 has an elongate, generally-cylindrical casing248, which has a tip 240 at the bottom with a structure andcharacteristics that are similar to the tool shown in FIGS. 2-4 . Aspindle 241 is fixed to and extends from the upper end of the casing248. The spindle 241 is constructed and arranged to attach to anindustrial machine such as a CNC milling machine (not shown), which canrotate and translate the tool downwardly with force against theworkpiece. The spindle 41 can be tailored to match a particularmachine's collet or chuck.

Within the bore 230 of the casing 248, the tool 220 has a compressionspring 225 seated between two thrust bearings 242. At the upper end, thespring 225 is connected to the thrust bearing by a coupler 243. At thelower end, the spring 225 is seated against one side of the pusher 222.The other side of the pusher 222 is seated in another thrust bearing242. The pusher 222 preferably has a shape and size that compliments theshape and size of the central bore 230 and permits the pusher 222 tofreely reciprocate within the bore 230. The compression spring 225controls the magnitude of the installation force of the pusher 222 onthe fastener 11, thereby reducing the possibility of inadvertentlymaking pressure marks on the back side of the panel. The force of thespring 225 should preferably be great enough to push the shank 15 of thefastener 11 through the interference zone of the hole 23. In a preferredembodiment, the compression spring 225 comprises a die spring.

Once the fastener 11 bottoms out in the receiving hole 23, the tool 220is further advanced downwardly and simultaneously rotated to enable thedisplacer(s) 227 to deform and push metal radially-inwardly over the topsurface 17 of the fastener flange 15, which attaches the fastener 11 tothe workpiece as seen in FIG. 3 .

In a preferred embodiment, the pusher 222 has axial bores 244 thatextend from one end of the pusher 222 to the other. The bores 244 createa fluid communication channel extending from the distal tip 240 of thetool 220, through the casing 248, through the spindle 241, and to avacuum source “V”. The vacuum source “V” creates suction at the tip 240of the tool to pick up and/or secure the fastener in the bore duringcrimping.

Because CNC control allows for variable speed and downward feed,discreet installation values for various workpiece materials can bedeveloped. The tool can be spun and advanced either simultaneously orseparately. For example, in a preliminary installation step the tool canbe spun so that the tip 240 makes incidental contact with the workpiece.The friction from this incidental contact will heat the area surroundingthe receiving hole and soften the workpiece material and thereby lowerthe rotational and compressive forces needed to install the fastener.

An installation tool in accordance with a further embodiment of theinvention is shown in FIG. 10 and is designated generally by referencenumeral 320. The tool 320 has an elongate, generally-cylindrical casing348, which has a tip 340 at the bottom with a structure andcharacteristics that are similar to the tool shown in FIG. 8 . A spindle341 is fixed to and extends from the upper end of the casing 348, whichserves the same function as described above with respect to theembodiment of FIG. 9

Similar to the embodiment shown in FIG. 9 , within the bore 330 of thecasing 348, the tool 320 has a compression spring 325 seated between twothrust bearings 342. At the upper end, the spring 325 is connected tothe thrust bearing by a coupler 343. At the lower end, the spring 325 isseated against one side of a fastener pusher 322. The other side of thepusher 322 is seated in another thrust bearing 342. Wedge-shapeddisplacers 327 extend axially from the tip 340 of the tool. In thisembodiment, the tool 320 includes a central, center punch 345 extendingaxially through the upper casing, through the pusher 322, and throughthe tip 340. The punch 345 has a pointed distal tip 346 and is used inconjunction with a donut-shaped hole in the same manner as describedwith respect to the embodiment of FIG. 8 . The punch 345 is isolatedfrom the pusher 322 and moves with the tool tip 20. The tool 320includes the same fluid communication channels as the tool shown in FIG.9 .

In the embodiments described above, the fastener 11 has a constructionsimilar to an internally-threaded nut or standoff. However, it should beappreciated that fasteners in accordance with preferred embodiments ofthe invention may have a construction similar to other known fastenerswhile incorporating the novel features described above. For example, atwo-part fastener arrangement is shown in the embodiment of FIG. 11 . Afirst fastener 411 a resembling a floating-pin retainer is shown inconjunction with a second fastener 411 b containing a magnetic catch 58for a pin 56. In these embodiments, each fastener 411 a, 411 b isinstalled in its own workpiece, such as cooperating panels of acommunications device or computer.

Each fastener 411 a, 411 b of the two part arrangement comprises a body413 a, 413 b, respectively, having an axial bore. The bottom of eachbody 413 a, 413 b includes a radially-protruding shank 415 a, 415 b,respectively, having a construction similar to the shank 15 of thefastener 11 described above with respect to FIGS. 1-3 . The fasteners411 a, 411 b are installed in blind holes 23 in each of the workpieces21 using the same installation techniques and tooling described above.During downward translation and rotation of the tool duringinstallation, material surrounding the blind hole 23 is cold deformedinwardly onto the top surface 417 a, 417 b of the shank 415 a, 415 b,respectively. When the panels are brought together, the pin 56 of onefastener 411 b mates with the catch 58 of the other fastener 411 a tojoin the panels. This arrangement of parts is particularly suited to thecasing of a laptop computer where visible marking on the outside of thecases is unwanted.

A fastener in accordance with yet a further preferred embodiment of theinvention is shown in FIGS. 12 and 13 and is designated generally byreference numeral 511. The fastener generally comprises a cylindricalbody 513 having an axial, threaded bore 512 that extends completelythrough the body 513 from the top 513 a to the bottom 513 c of the body513. The bottom of the body 513 includes a radially-protruding shank 515having a top surface 517, a side surface 518, a chamfer 514, and abottom surface 516. In a preferred embodiment, the top surface 517 ofthe shank 515 is generally annular and lies in a plane that isorthogonal to the central axis of the body, and parallel to the top 513a and bottom 513 c of the fastener body 513. Preferably, the side walls518 are cylindrical, and co-axial with and parallel to the side walls513 b of the body 513. Preferably the surface of the chamfer 514 extendsat an angle that is skew to the central axis of the body 513, and tapersdownwardly-inwardly from the side surface 518 towards the bottom of thebody 513. In a preferred embodiment, the bottom surface 516 of the shank515 is flat, annular and lies in a plane that is orthogonal to thecentral axis of the body 513, and parallel to the top 513 a and bottom513 c of the body 513. In a preferred embodiment, the bottom surface 516is continuous and co-planar with the bottom 513 c of the body 513.

In contrast to the notches 19 of the embodiment shown in FIG. 1 , theshank 515 includes a plurality of lugs 560 to provide torque resistanceonce installed in the workpiece. Metal from the workpiece is colddeformed onto the top surface 517 of the shank in between the lugs.Depending on the thickness of the workpiece, material may also be colddeformed onto the top of the lugs 560. In a preferred embodiment, thelugs 560 are equally spaced around the perimeter of the shank. In thisembodiment, the lugs 560 are depicted as rectangular blocks but may haveany shape that will provide resistance to rotation of the fastenerwithin the hole.

From the foregoing it will be apparent to those of skill in the art thatthe objects of the invention have been achieved. Furthermore, it will beapparent to those of skill in the art that there are many variations andadaptations of the embodiments disclosed all of which fall within thescope and spirit of the invention which shall be determined only by theclaims and their legal equivalents.

What is claimed is:
 1. A fastener installation tool, comprising: a. acasing having a top end, a bottom end, and a central rotational axis; b.a spindle fixed to said top end of the casing and adapted for affixationto a rotary and vertically reciprocal element of an industrial machine;c. a tip at the bottom end of the casing adapted for deforming aworkpiece as the tip rotates and is pressed against the workpiece; andd. an axial bore within said tip adapted for holding a fastenerinstalled by the tool.
 2. The tool of claim 1, wherein said tip has adistal end surface orthogonal to the axial bore which is constructed andarranged to engage and deform the workpiece.
 3. The tool of claim 2,including a displacer on said distal end surface.
 4. The tool of claim3, wherein said displacer is vertically tapered along an arcuate ridgecentered about said axial bore from a back end of greatest height downto a front end of minimum height where the ridge meets the end face. 5.The tool of claim 4, wherein an inside edge of said displacer ischamfered from the ridge to the axial bore.
 6. The tool of claim 5,wherein said displacer is chamfered from the displacer ridge to an outeredge of the displacer.
 7. The tool of claim 6, wherein the width of saiddisplacer is tapered such that the front end of said displacerintersects said distal end surface at a point.
 8. The tool of claim 7,including two displacers located 180 degrees apart around the centralrotational axis.
 9. The tool of claim 8, wherein said displacers aresubstantially identical and wherein the length of each displacer extendsapproximately 90 radial degrees around the central rotational axis fromthe front end to the back end.
 10. The tool of claim 1, including fluidcommunication channels extending from the spindle to the tip forproviding a vacuum at the tip when the spindle is connected to a vacuumsource, wherein the vacuum holds the fastener within the tip bore whilethe tool body rotates.
 11. The tool of claim 10, further including acenter punch extending axially through said axial bore and the fastenerwhen it occupies the tip.
 12. The tool of claim 1, further including CNCmilling machine connected to said spindle.
 13. The tool of claim 1,further including a spring-biased fastener pusher constructed andarranged to apply an axial insertion force on a fastener within the tip.14. A fastener installation tool, comprising: a. a cylindrical tool bodyhaving a first closed axial end, cylindrical side walls, and a secondopen end having a central, axially-extending blind bore; b. awedge-shaped displaces extending axially from the open end of the toolbody and surrounding the opening of the bore; c. a compression springseated at one end in the bottom of the bore and connected at the otherend to a pressure plate having a shape and size that compliments theshape and size of the central bore and permits the pressure plate tofreely reciprocate within the bore; and d. wherein when the fastener isinserted into a blind hole in a workpiece, the tool engages the fastenerand the workpiece, and the tool is rotated, the displacers of the toolare constructed and arranged to cold deform inwardly the materialsurrounding the blind hole onto a material receiving portion of afastener.
 15. The tool of claim 14 wherein the tool is configured tocold deform a central raised area in the bottom of the blind hole intothe fastener.